Astronomers have discovered a newborn planet in a solar system that is still in the process of forming - the first example of this ever found.

Planets are believed to develop within swirling discs of dust and gas around nascent stars.

So studying very young examples could tell astronomers much about the birth and evolution of planetary systems - including our own Solar System.

Details of the discovery, by a team in Germany, appear in the journal Nature.

Johny Setiawan, from the Max Planck Institute for Astronomy in Heidelberg, and colleagues say the planet has nearly 10 times the mass of our Jupiter; and it circles TW Hydrae, a nearby young star which is only eight to 10 million years old.

The planet orbits the star with a period of 3.56 days at a distance of about six million km (four million miles), inside the inner rim of the system's dusty disc.

The researchers tell Nature the study shows how planet formation can occur quickly before a burgeoning star has had time to clear debris from its neighbourhood.

"This demonstrates that planets can form within 10 million years, before the
disc has been dissipated by stellar winds and radiation," they write.

The observations were made using the 2.2m Max-Planck-Gesellschaft telescope at the European Southern Observatory's La Silla facility in Chile.

TW Hydrae is is situated about 182 light-years away in the constellation Hydra.